This invention relates to an apparatus for active reduction of vertical vibrations of vibrating mass, especially of motor vehicle components, driver and passengers exposed to a non-periodic (random, stochastic) excitation and bound in vertical direction to a base springing joint provided with a compressed-air springing unit having a connection pipe for compressed-air supply and removal.
It is known that at projecting arrangements which are exposed to vibrations, particularly those through which these vibrations are transmitted onto human body, a solution of most effective reduction of harmful vertical vibrations is aimed at. Actually, most of such problems appear in motor vehicles, and therefore the so called pending seats, cabins and the like are to be provided.
Arrangements for reduction of vertical vibrations of motor vehicle elements by additional energy, as known in prior art, are confined to the above structures of traveler's vehicles, whereat hydraulic systems are used. As results of these solutions, very complicated and expensive constructions have been presented, which, just due to the price, have not been accepted for mass production.
On certain vehicles, e.g. buses, the hinging systems based on compressed air are used, the control of which is based on the supply of compressed air into or its removal from the compressed-air springing element. This control is provided for controlling the vehicle level when the loading is changed or unequal, for example, and not capable of reacting quickly, especially to random excitations.
The vibration systems of passive type which have been used hitherto for reducing vertical vibrations are confined to a compromise as regards the choice of the damping factor. This factor being high, the influence of the vibration system resonance is well reduced, but the damped mass is strongly influenced by high frequencies. On the contrary, when said factor is low, the damped mass is less influenced by high frequencies, but at resonance a high extension of amplitude of oscillation appears. Said compromise is always present and the results achievable by applying the alinear elements of the springing system are not considerably better. When a larger mass is in question, e.g. an above structure of traveler's vehicle, this compromise is simultaneously conditioned by driving security which requests as small loading variation on shaftings as possible.
One of the known solutions or reducing vertical vibrations at a seat using passive elements of the springing system is a pending seat construction, which, by the fundamental frequency of the vibrating system of the seat arranged below the fundamental frequency of vibrating system of the vehicle and thereby performing a little smaller excitation as well as considering lower sensibility of human at lower frequencies, registers somewhat better results, but they are unsatisfactory yet.